This invention relates to a monitoring method and device for monitoring operations of a mechanism, such as an injection device of an injection molding machine, driven by an actuator and, more particularly, to a monitoring data display method and device in which analog data variable in accordance with lapse of time is subjected to multipoint sampling and the data is displayed in or on a recorder or display tube.
With a conventional technique of recording of an analog data regarding a rapidly variable operation of a mechanism driven by an actuator, the analog data could be recorded only by the use of a fast acting recorder. However, in a conventional method of multipoint sampling and display of such data, when operation time and/or operation speed of the drive mechanism varies, a length of an axis of abscissa representing time (lapse of time) must be expanded or shortened at a time of monitoring the whole sampling numbers and the comparison of this data has to be made by changing the sampling mode, i.e. output frequency to a recorder or a display tube, every time the operation time and/or operation speed varies.
In another method for visually deciding the fact whether or not a profile of the detected data accords with a first displayed operation condition at a time of reproduction of a certain operation condition, there was not any convenient device suitable for comparing a reference profile with a sample profile and upper most and lowermost profiles of the reference with the sample profile by superposing the profiles. Moreover, in a case where the profile of the detected data exhibits operational characteristics different from the reference profile, it was difficult to clearly display a stage at which the difference of the characteristics occurred during the operation of the drive mechanism, i.e. first, intermediate, or final stage of the operation.